Hydro cyano and cyano fullerene derivatives

ABSTRACT

Novel acidic hydrogen cyano fullerenes and cyano fullerenes are disclosed that may be utilized as components in a proton conducting membrane (PCM). In particular, C 60 H(CN) n , wherein n&gt;1, and C 60 (CN) n , wherein n&gt;2, species are provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of copending application Ser. No.11/067,599, filed on Feb. 25, 2005.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

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INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC

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NOTICE OF MATERIAL SUBJECT TO COPYRIGHT PROTECTION

A portion of the material in this patent document is subject tocopyright protection under the copyright laws of the United States andof other countries. The owner of the copyright rights has no objectionto the facsimile reproduction by anyone of the patent document or thepatent disclosure, as it appears in the United States Patent andTrademark Office publicly available file or records, but otherwisereserves all copyright rights whatsoever. The copyright owner does nothereby waive any of its rights to have this patent document maintainedin secrecy, including without limitation its rights pursuant to 37C.F.R. §1.14.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention pertains generally to novel proton conducting membranes(PCMs) and the components utilized to produce these PCMs. Moreparticularly, the subject invention relates to novel PCMs and theirconstituent components comprising hydrogen cyano fullerenes(HC₆₀(CN)_(x) (or C₆₀H(CN)_(x)) as a proton-source agent and oftenpoly(ethylene oxide) attached fullerenes (C₆₀(PEO)_(y)) as mixing agentsto facilitate PCM formation with a host polymer.

2. Description of Related Art

The subject invention is utilized as a major component of a polymerelectrolyte fuel cell (PEFC). PEFCs are generally comprised of threemajor components: the anode; the proton conducting membrane (PCM, thesubject invention area); and the cathode. The PCM plays a critical roleof transporting a proton from the anode to the cathode. It has to behighly proton conductive and also mechanically, thermally, andchemically stable. Water is produced at the interface between thecathode and the membrane. This water can be problematic, as discussedbelow, in operation of a PEFC. Lack of suitable membrane availabilityhas been hindering the commercialization of PEFC. Water management isone of the most difficult issues in operating a PEFC. The water in thePEFC is produced as a product at the cathode side in PEFC. A breakdownin water balance between production and loss of water at the cathodeside often results in water flood, while the anode interface with themembrane may suffer from water depletion due to water transportationtoward the cathode side. Both the flood and the depletion may increasethe cell over-potential, which results in loss of power. Furthermore,the most commonly used PCMs are based on sulfonated perfluoropolymersthat need to be fully humidified to be functional during the operationof the PEFC. Thus, these sulfonated perfluoropolymers not only require ahumidifier, but also need an even distribution of water across themembrane, which becomes an additional concern because of the membrane'shigh dependence on water.

Dry operation of PEFC may alleviate some of the water managementproblems. In fact, there is a strong demand in the auto industry as wellas the distributed power generation industry for PEFC functional underlow relative humidity (RH) (<50% RH). [Mathias, M.; Gasteiger, H.;Makharia, R.; Kocha, S.; Fuller, T.; Xie, T.; Pisco, J. Preprints ofSymposia—American Chemical Society, Division of Fuel Chemistry 2004,49(2), 471-474.] Currently, no commercially available PCM meets thisdemand. NAFION, the industrial standard PCM by DuPont, is widely used inPEFC; yet it is sensitive to humidity, a very undesirablecharacteristic. Other existing proton conducting membranes, commerciallyavailable or under development, are as good or even better than NAFIONunder fully humidified condition, but very few outperform NAFION underlow humidity conditions.

One existing PCM is disulfonated poly(arylene ether sulfone) copolymer(BPSH) developed by McGrath and coworkers. [Wang, F.; Hickner, M.; Kim,Y. S.; Zawodzinski, T. A.; McGrath, J. E. J. Membr. Sci. 2002, 197,231.] Though BPSH is thermally stable and mechanically durable, andwidely used as one of the most advanced alternative PCM, its protonconductivity under low RH (<80%) is lower than that of NAFION. Lack ofmembranes capable of functioning under low RH, (i.e., maintaining highconductivity, ˜10⁻¹ S cm⁻¹) has been an obstacle to bringing PEFC tomarket. The challenge for the industry is how to improve theconductivity of PCMs, where water plays a vital role in protontransportation, under dry condition.

A typical approach previously attempted to improve the conductivity ofPCMs under low RH has been to increase the degree of sulfonation in thePCM in an attempt to increase the overall conductivity. [Tchatchoua, C.;Harrison, W.; Einsla, B.; Sankir, M.; Kim, Y. S.; Pivovar, B.; McGrath,J. E., Preprints of Symposia—Am. Chem. Soc., Div. of Fuel Chem. 2004,49(2), 601.] The problem with such an approach is that the membranetends to swell more with a higher degree of sulfonation, which isdetrimental in operation of fuel cell since the dimensional stability ofthe PCM is a key to the operation. Also, there is synthetic difficultyassociated with increasing degree of sulfonation. Furthermore, there isa theoretical limit to the conductivity due to the sulfonyl groups(—SO₃H) in the membrane.

An existing alternative approach to improve proton conductivity is afabrication of composite membranes based on the conventional water-basedPEM and inorganic/organic additives including SiO₂ and heteropolyacids(HPA). [Shao, Z-G.; Joghee, P.; Hsing, I-M. J. Membr. Sci. 2004, 229,43.] Especially, HPA has been widely used to improve the performance ofproton conducting membranes. [Herring, A. M.; Turner, J. A.; Dec, S. F.;Sweikart, M. A.; Malers, J. L.; Meng, F.; Pern, J.; Horan, J.; Vernon,D. Abst. 228th Am. Chem. Soc. National Meeting, Philadelphia, Pa., Aug.22-26, 2004 FUEL-053.] The problems with HPA, however, are that it iswater-soluble, thus leaches out, and the proton conductivity issensitive to humidity. [Katsoulis, D. E. Chem. Rev. 1998, 98, 359.]Hence, immobilization of HPA in a membrane is a particularly importantissue. [Kim, Y. S.; Wang, F.; Hickner, M.; Zawodzinski, T. A.; McGrath,J. E. J. Membr. Sci. 2003, 212, 263.]

An existing and more radical approach to improve proton conductivity isto replace water altogether. PCM with low volatile solvents such asimidazole have been utilized to replace water. [Kreuer, K. D.; Fuchs,A.; Ise, M.; Spaeth, Maier, M. J. Electrochim. Acta 1998, 43, 1281.]Though the proton conductivity of 10⁻² S cm⁻¹ has been achieved at hightemperatures, imidazole is known to poison the Pt catalyst and also issubject to diffusing out of the membrane, which is currently fixedthrough chemical attachment to a host polymer. [Schuster, M. F. H.;Meyer, W. H.; Schuster, M.; Kreuer, K. D. Chem. Mater. 2004, 16, 329.]Also, work exists in which a polybenzimidazole membrane was doped byH₃PO₄ (PBI/H₃PO₄). [Fontanella, J. J.; Wintersgill, M. C.; Wainright, J.S.; Savinell, R. F.; Litt, M. Electrochimica Acta 1998, 43, 1289.] Yet,H₃PO₄ is known to be leached out by water on the cathode side.Improvement of the performance of a PBI/H₃PO₄ membrane has been achievedthrough the use of polyphosphoric acid, however, the poor performance atlow temperature and leaching out of H₃PO₄ by water condensation remainunsolved. [Zhang, H.; Chen, R.; Ramanathan, L. S.; Scanlon, E.; Xiao,L.; Choe, E-W.; Benicewicz, B. C. Prep. Div. Fuel Cehm. Am. Chem. Soc.,Philadelphia, Pa., Aug. 22-26, 2004, 49, 588.] In another approach toreplace water, inorganic solid acids such as CsHSO₄ have been used.[Haile, S. M.; Boysen, D. A.; Chisholm, C. R. I.; Merle, R. B. Nature(London, United Kingdom) 2001, 410, 910.] However, there are concernsregarding this solid acid: reduction of the sulfur in the CsHSO₄electrolyte may occur over time, the reaction with hydrogen formshydrogen sulfide, and also a poisoning to the Pt catalyst may occur.Other solid acids may be less problematic, but the stability of thematerials remain problematic since the operation temperatures for thesesolid acids are close to their thermal decomposition temperatures. Thus,anhydrous (non-water) membranes have not reached a practical stage foroperation of PEFC.

Although limited details are provided, a journal article by Saab et al.provides the first limited experimental data on the ionic conductivityof chemically functionalized fullerene. [Saab, A. P.; Stucky, G. D.;Passerini, S.; Smyrl, W, H, Fullerene Science and Technology, 1998, 6,227.]

U.S. Pat. No. 6,495,290 B1 discloses proton conducting materialscomposed of carbon materials including fullerenes with functional groupsattached to them. [Hinokuma, K.; Ata, M.; J. Electrochem. Soc. 150(2003) A112.] It is claimed that the '290 materials can be used for PCMunder dry condition. The best conductivity achieved using theirmaterials under dry condition was 10⁻⁴ S cm⁻¹, not very high foroperation of a PEFC. The difference from the current subject inventionis that: (i) the subject invention's performance is much higher, ˜10⁻² Scm⁻¹, than theirs, though the subject invention PCM also uses differentfullerene-based materials; (ii) their materials lose performance as thecontent of their fullerenes in the PCM decreases below 80 wt %, whilethe subject invention PCM exhibits high performances with only 20 wt %of the subject novel fullerenes in a host polymer; and (iii) the subjectinvention functional groups attached to the fullerenes are completelydifferent from those listed, suggested, or taught in '290. Furthermore,the '290 approach is to use fullerene as a carrier of proton hoppingsites such as the OH groups for proton transportation where a proton istransported between the functional groups attached to fullerene. On thecontrary, the subject invention uses novel fullerene derivatives asstrong proton sources, i.e., the function in the subject invention isdifferent from '290. Thus, a difference is that the '290 inventionrelies on the functional groups on fullerenes for proton transportation,while the subject invention uses water as the proton transportationmedium and the derivatized fullerenes promote proton conduction as aproton-source, especially under low humidity. Additionally, when cyanogroups (—CNs) are mentioned in '290 the cyano groups are considered tobe only “electron attractive groups” that may be “introduced togetherwith” the other listed critical functional groups and only serve toassist the non-cyano functional groups that must be present too.

BRIEF SUMMARY OF THE INVENTION

An object of the present invention is to describe a PCM having carbonclusters modified with both hydrogen and cyano moieties.

Another object of the present invention is to present a PCM with onecomponent a hydrogen and cyano derivatized fullerene.

An additional object of the present invention is to relate a derivatizedcarbon cluster mixing agent utilized in producing a PCM by which themixing agent facilitates blending of a host polymer and a carbon clustermodified with both hydrogen and cyano moieties.

A still further object of the present invention is to disclose apoly(ethylene oxide) derivatized fullerene mixing agent utilized inproducing a PCM by which the mixing agent facilitates blending of a hostpolymer and a hydrogen and cyano derivatized fullerene.

Yet another object of the present invention is to make known a PCMproduced by mixing a hydrogen cyano fullerene with a host polymer.

Still yet another object of the present invention is to explain a PCMproduced by mixing a hydrogen cyano fullerene proton-source agent, apoly(ethylene oxide) mixing agent, and a host polymer.

Generally, the subject invention comprises a PCM having a host polymerand a proton-source agent. The proton-source agent comprises a carboncluster derivative, wherein the carbon cluster is derivatized with bothhydrogen and cyano moieties. The carbon cluster derivative comprisesfrom about 0.01 wt % to about 80 wt % of the PCM and may be physicallyblended with the host polymer or attached to the host polymer. Althoughany suitable carbon cluster (such as a fullerene family member orequivalent molecule such as a carbon nano-tube, open or closed carboncage-molecule, and the like) that does not interfere with the structuraland functional characteristics of the PCM is contemplated to be withinthe realm of this disclosure. The preferred carbon cluster is usuallyone of the family of carbon structures known as fullerenes and thereforethe carbon cluster derivative usually comprises a hydrogen cyanofullerene.

A host polymer is any polymer utilized to generate a functioning PCMsuch as poly(ethylene oxide) and the like.

When a carbon cluster derivative is blended with a host polymer, thecomposition may further comprise a mixing agent to promote blending ofthe carbon cluster derivative with the host polymer. The subject mixingagent comprises one or more poly(ethylene oxide) side chains attached toa carbon cluster, wherein the carbon cluster preferably comprises afullerene family member or equivalent molecule such as a carbonnano-tube, open or closed carbon cage-molecule, and the like.

It is noted, in general, that the subject PCMs, comprised of the novelsubject components, possess an improved performance over existing PCMsunder low humidity, <50% relative humidity (RH), and at high temperature(>120° C.) in the operation of polymer electrolyte fuel cells (PEFC).

Further objects of the invention will be brought out in the followingportions of the specification, wherein the detailed description is forthe purpose of fully disclosing preferred embodiments of the inventionwithout placing limitations thereon.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

The invention will be more fully understood by reference to thefollowing drawings which are for illustrative purposes only:

FIG. 1 shows chemical representations for two specific forms of hydrogencyano fullerenes, C₆₀H(CN) and C₆₀H(CN)₃, the general acid source in thesubject invention, wherein a general formula is C₆₀H(CN)_(n) with “n”running from 1 to about 60.

FIG. 2 shows chemical representations for two specific forms ofpoly(ethylene oxide), Mono PEOC₆₀ and Di PEOC₆₀, general mixing agentsin the subject invention, wherein a general formula isC₆₀{N(CH₂CH₂O)_(n)CH₃}_(m) with “n” running from 1 to about 45 orgreater and “m” running from 1 to 2 or greater.

FIG. 3 shows a chemical representation for a general mixing agent in thesubject invention, wherein the general formula isC₆₀{CH₂C₆H₄O(CH₂CH₂O)_(n)CH₃}_(m) with “n” running from 1 to about 45 orgreater and “m” running from 1 to about 8 or greater.

FIG. 4 shows a synthesis scheme for the compounds C₆₀H(CN), C₆₀H(CN)₃,C₆₀(CN)₂, and C₆₀(CN)₄.

FIG. 5 shows a synthesis scheme for exemplaryC₆₀{CH₂C₆H₄O(CH₂CH₂O)_(n)CH₃}_(m) (multi-PEO fullerene [PEO_(m)C₆₀]derivatives with various length sizes and numbers of PEO_(m) chains)molecules by atom transfer radical addition (ATRA) reactions.

FIG. 6 shows the azide addition of PEO-azide to fullerene synthesisscheme utilized to produce exemplary C₆₀{(NCH₂CH₂O)_(n)CH₃}_(m)molecules, made with numbers of and various lengths of PEO chains.

FIG. 7 shows the proton NMR spectra for C₆₀H(CN) and C₆₀H(CN)₃.

FIGS. 8A, 8B, and 8C show the IR spectra for C₆₀, C₆₀H(CN), andC₆₀H(CN)₃, respectively.

FIG. 9 shows a proposed reaction mechanism for the synthesis ofpoly(ethylene oxide) attached fullerenes.

FIG. 10 shows the proton NMR spectrum for multi-PEO fullerenes.

FIGS. 11A and 11B show EPR spectra for organic (11A) and transitionmetal (11B) radical signals from samples of (PEO₃)_(m)C₆₀.

FIGS. 12A and 12B show MALDI-TOF spectra of (PEO₃)_(m)C₆₀, (12A) and(PEO₈)_(m)C₆₀ (12B).

FIG. 13 shows the UV—VIS spectra of Di (PEO₁₆)C₆₀ in various solventsand thin film.

DETAILED DESCRIPTION OF THE INVENTION

Referring more specifically to the drawings, for illustrative purposesthe present invention is embodied in novel proton conducting membranes(PCMs) produced from various suitable combinations of the chemicalstructures generally shown in or related to those depicted in FIG. 1through FIG. 3. It will be appreciated that the PCMs may vary as totheir exact component percentages, without departing from the basicconcepts as disclosed herein.

Generally, the subject invention comprises PCMs having novelproton-source agents and may also contain novel mixing agents that aidin blending the proton-source agents with the host polymer. Contrary toexisting PCMs that derive their acidity from weaker acid species likethe SO₃H group, a typical acid group found on traditional PCMs (pKa ofC₆H₅SO₃H is approximately 2, while the pKa of C₆₀H(CN)₃ is approximately0.7), the subject proton-source agents utilize stronger hydrogen andcyano acid moieties, yet the subject invention still uses water as aproton transportation medium. To facilitate proton conduction in thePCM, novel proton-source agents are employed that comprise hydrogencyano derivatized carbon clusters that structurally and functionallyincorporate into PCMs. Various types of carbon clusters are possible(see U.S. Pat. No. 6,495,290 B1, which is herein incorporated byreference, for a description of some carbon clusters commonly used orthat may be used in forming PCMs), however, a preferred embodiment ofthe subject invention comprises carbon clusters that are specificallyhydrogen cyano fullerenes (HCF; see FIG. 1) which are very strong acids.An HCF functions as an acid source in a PCM in which HCF is mixed in ahost polymer or host polymer and a mixing agent (see FIGS. 2 and 3).Strong acids result in higher concentrations of protons, the ion carrierin PCM, in general, due to the higher proton dissociation of the acid;thus, the subject HCFs increase overall conductivity of a PCM, liftingconductivity versus relative humidity (RH). Stronger acids can also holdmore so-called “bound water” which may be used for protontransportation, especially beneficial under low RH. The importance ofbound water in a PCM has been recognized. [Kim, Y. S.; Dong, L.;Hickner, M. A.; Glass, T. E.; Webb, V.; McGrath, J. E. Macromolecules2003, 36, 6281.] This may decrease the slope of found in traditionalconductivity vs. RH curves, which lifts the conductivity under low RHrelative to that under higher RH.

It is noted that the hydrogen and cyano functional groups may bedirectly connected to the carbons within the carbon cluster/fullerene orphysically displaced from the carbon cluster/fullerene surface by aspacer moiety such as methylene(s) or similar appropriate spacerunit(s).

One should appreciate that the proton-source agent may be directly orindirectly chemically coupled to the host polymer and not merelyphysically blended with the host polymer. Standard chemical couplingprocedures may be utilized to generate such linkages.

Often included in the subject PCMs are mixing agents that promote theblending of the subject HCF in with a host polymer, thus allowing thesubject HCFs to be well-dispersed throughout the membrane to achieve themaximum performance as a PCM.

More specifically, the subject invention comprises a hydrogen cyanofullerene acid source/proton-source agent, a host polymer, and, ifdesired, a poly(ethylene oxide) fullerene mixing agent.

ACID SOUCE/PROTON-SOURCE AGENT—Hydrogen cyano fullerenes—One of thesubject materials may be expressed in general form as C₆₀H(CN)_(n). FIG.1 illustrates two typical and non-limiting examples, hydrogen mono-cyanofullerene (C₆₀HCN) and hydrogen tri-cyano fullerene (C₆₀H(CN)₃) (seeFIG. 4 for additional examples). It must be stressed that fullerenescome in other forms than the common C₆₀ species and that these otherfullerenes (C₂₀, C₇₀, C₇₆, C₈₄, C₈₆, and the like) and equivalenthydrogen cyano derivatives are also within the realm of this disclosure.The composition of HCF in a host polymer can be in an extremely widerange (which differs dramatically from existing acid sources utilized inPCMs), but preferably from about 0.01 wt % to about 80 wt %. Again, HCFcan be either blended in the host polymer or chemically attached to it.

The exemplary compounds C₆₀H(CN), C₆₀H(CN)₃, C₆₀(CN)₂, and C₆₀(CN)₄ weresynthesized according the synthesis scheme shown in FIG. 4 (see below inthe “Examples” section for details).

MIXING AGENT—Poly(ethylene oxide) attached fullerenes—The mixing agentswhich promote a blending of the hydrogen cyano fullerenes into a hostpolymer are comprised of poly(ethylene oxide) attached fullerenes. Thesematerials may be expressed as C₆₀{(NCH₂CH₂O)_(n)CH₃}_(m) andC₆₀{CH₂C₆H₄O(CH₂CH₂O)_(n)CH₃}_(m), wherein “n” and “m” range from 1 toabout 45 and from 1 to about 8 or greater, respectively. FIGS. 2 and 3illustrate some non-limiting examples. The actual chemical linkage ofthe poly(ethylene oxide) moiety to the fullerene may vary as long as thelinkage means does not interfere with the proper functioning andstructural integrity of the generated PCM. In general, FIG. 2illustrates nitrogen facilitated linkages to generate mono and dipoly(ethylene oxide) derivatives of fullerene (mono- and di-C₆₀poly(ethylene oxide) (PEOC₆₀), respectively). FIG. 3 depicts phenyllinkages from multiple poly(ethylene oxide)s to a C₆₀ poly(ethyleneoxide) (PEOC₆₀) core. Again, it is stressed that fullerenes come inother forms than the common C₆₀ species and that these other fullerenes(C₂₀, C₇₀, C₇₆, C₈₄, C₈₆, and the like) and equivalent poly(ethyleneoxide) derivatives are also within the realm of this disclosure.

The exemplary C₆₀{CH₂C₆H₄O(CH₂CH₂O)_(n)CH₃}_(m) (multi-PEO fullerene[PEO_(m)C₆₀] derivatives with various length sizes and numbers ofPEO_(m) chains) molecules were designed and synthesized by atom transferradical addition (ATRA) reactions (see FIG. 5). It is noted thatapparently a limited amount of bromine is incorporated into the finalfullerene compounds (the bromine is not indicated in the FIG. 3structure since, apparently, it is the PEO_(m) chains that produce themixing agent's blending properties and not the small amount of bromine).

The exemplary C₆₀{(NCH₂CH₂O)_(n)CH₃}_(m) molecules, made with variouslength of PEO chain, were synthesized by azide addition of PEO-azide tofullerene (as seen in FIG. 6). The synthesis followed the procedure fromliterature. [Hawker, C. J., Saville, P. M., and White, J. W., J. Org.Chem. 1994, 59, 3503 and Huang, X. D., Goh, S. H., and Lee, S. Y.,Macromol. Chem. Phys. 2000, 201, 2660.] However, unlike those fullereneazide addition reactions, in which mono-azide addition products arealways the major products, here we found bis-azide addition productswere the major products in all the reactions. Only trace amount ofmono-azide addition products were detected (see below for details).

HOST POLYMER—The host polymers in which hydrogen cyano fullerenes (HCF)are mixed (and, if selected, also one or more suitable fullerenederivatized mixing agents) to compose a PCM can be any polymers as longas they are thermally, chemically, and mechanically stable, and durablewhen mixed with HCF under typical fuel cell operation conditions. Theycan be either proton conductive or non-conductive. The examples includeNAFION (DuPont), poly(arylene ether sulfone), poly(phosphazines),polyethers, poly(vinyl pyrrolidone), poly(phenylene ether), and otherequivalent materials.

EXAMPLES Example 1 Preparation of the Acid Source/Proton-Source Agent(Hydrogen cyano fullerenes)

Again, C₆₀H(CN) and C₆₀(CN)₂ were synthesized according the literature(Keshavarz, M., Knight, Srdanov, G, and Wudl F., JACS 1995, 11371).

In particular, for the preparation of C₆₀H(CN)₃ a degassed solution ofNaCN (20 mg, 1.2 eq.) in DMF (20 mL) was added to a degassed solution ofC₆₀(CN)₂ (260 mg, 0.34 mmol.) in ODCB (30 mL) via canula at roomtemperature. After being stirred 3 minutes, the resultant deep greensolution was treated with perchloric acid (0.25 mL). After 30 minutes,the brown mixture was concentrated and the solid obtained waschromatographed on silica gel (CS₂/Toluene (1:3)), C₆₀H(CN)₃ wasdissolved in ODCB and crystallized by adding ethyl ether or methanol(51% yield). It is noted that during the synthesis of C₆₀H(CN)₃, thatthe acidity of trifluoroacetic acid (pKa: 0.52) is not strong enough toprotonate the C₆₀(CN)₃ ⁻ and a stronger acid like perchloric acid (pKa:−1.6) was needed to protonate efficiently this anion. This approach madeit possible to obtain C₆₀H(CN)₃ in a 51% yield (double that obtainedfrom TFA).

For the preparation of C₆₀(CN)₄ degassed solution of NaCN (30 mg, 1.2eq.) in DMF (40 mL) was added to a degassed solution of C₆₀(CN)₂ (400mg, 0.52 mmol.) in ODCB (60 mL) via canula at room temperature under N₂.After being stirred 3 minutes, a degassed solution of p-toluenesulfonylcyanide (189 mg, 2 eq.) in toluene (30 mL) was added via canula to theresultant deep green solution. After 4 hours, the brown mixture wasconcentrated and the solid obtained was chromatographied on silica gel(CS₂/Toluene (1:3)). The solvents were removed and C₆₀(CN)₄ wasdissolved in ODCB and crystallized by adding ethyl ether or methanol(22% yield).

Characterization of C₆₀H(CN)₃ and C₆₀(CN)₄: ¹H NMR: By NMR, thecharacterization of C₆₀H(CN)₃ and C₆₀(CN)₄ are more difficult than forC₆₀H(CN) and C₆₀(CN)₂ because they were obtained in the form ofdifferent regioisomers. As seen in FIG. 7A, the NMR ¹H spectrum ofC₆₀H(CN) gives one singlet at 6.65 ppm because there is only one isomer.In the case of C₆₀H(CN)₃ (see FIG. 7B), thirteen singlets appear between5.8 and 6.5 ppm corresponding to the proton of each of the differentregioisomers.

IR: As seen in FIG. 8, the drift IR spectra of C₆₀H(CN)₃ (FIG. 8B) andC₆₀(CN)₄ (FIG. 8C) show clearly the cyano group (2232 cm⁻¹) that doesnot appear for C₆₀ (1430, 1180, 540 and 525 cm⁻¹) (FIG. 8A).

Mass spectrum (not shown): The negative MALDI-TOF spectra of C₆₀H(CN)₃and C₆₀(CN)₄ show mainly the parent peaks.

Results from differential pulse voltammetry measurements of subjectcompounds (not shown): As the number of cyano groups on the C₆₀derivatives increased, it became easier to reduce the compounds. Hence,the attachment of four cyano groups causes a positive shift of 320 mV,compared to C₆₀. The hydro cyano fullerene derivatives compounds are notsoluble in hydroxylic solvents (such as water, ammonia, acetic acid,ethanol, etc.), making a direct titration impossible. The method used inthe literature to determinate the pKa of hydro fullerene(s) is throughvoltammety. In order to obtain information about the acidity ofC₆₀H(CN)_(x), different bases were added to solutions of thesecompounds. If the acidity of C₆₀H(CN)_(x) was strong enough to protonatethe base added and form C₆₀(CN)_(x) ⁻, the first reduction peak forC₆₀H(CN)_(x) should decrease in height because C₆₀(CN)_(x) ⁻ is muchmore difficult to reduce, its first step of reduction being close to thesecond reduction step of C₆₀H(CN)_(x). Four bases were used: the sodiumsalts of acetic acid, chlroroacetic acid, dichloroacetic acid andtrifluoroacetic acid. In water, the pKa values of the acids are 4.75,2.87, 1.35 and 0.52, respectively. The addition of 1 mol of acetate orchloroacetate in DMSO per mol of C₆₀H(CN) in ODCB resulted in completedisappearance of the first reduction peak of C₆₀H(CN), signifying thatC₆₀H(CN) is a much stronger acid than chloroacetic acid. By contrast,addition of 1 equiv of sodium dichloroacetate caused only a 20%reduction in the height of the C₆₀H(CN) peak and no decrease with addedtrifluoroacetate. This implies that the pKa of C₆₀H(CN) is betweenchlroroacetic acid (pKa: 2.87) and dichloroacetic acid (pKa: 1.35). Thesame experiments were performed with C₆₀H(CN)₃. For this compound, theaddition of 1 mol of acetate, chloroacetate or dichloroacetate per molof C₆₀H(CN)₃, resulted in complete disappearance of the first reductionpeak of C₆₀H(CN)₃, signifying that C₆₀H(CN)₃ is a much stronger acidthan dichloroacetic acid (pKa: 1.35) but less than trifluoroacetic acid(pKa: 0.52) since only half of the C₆₀H(CN)₃ reduction peak disappeared.Thus, C₆₀H(CN)₃ (pKa around 0.7) is a much stronger acid than C₆₀H(CN)(pKa around 2.5).

Example 2 Preparation of the Mixing Agent (Poly(ethylene oxide) AttachedFullerenes)

Poly(ethylene oxide) monomethyl ethers (for example, where n˜3, 8, 12,17, and 45) were functionalized with benzyl bromide in three steps asshown immediately below in Scheme 1:

As seen in FIG. 5, in the ATRA step, the fullerene was first dissolvedin o-dichlorobenzene (ODCB) in a pressure vessel, then 8 equivalents ofPEO-benzylbromide (one equivalent yields a mono-PEO final product andthe like) and 2,2′-bipyridine were added and the solution was degassedfor 10 minutes. After 8 equivalents of Cu(I)Br was added, the vessel wassealed and heated to 110° C. for 24 h until a green precipitate formed.Air was bubbled through the reaction mixture to precipitate un-reactedcopper (I) complex. Upon filtration, the solution was concentrated andprecipitated into 200 ml of ether. The product, with “n” final PEOchains and “y” bromines, was collected by filtration as a brown oil orsolid (final yield was ˜90%).

The proposed mechanism for the reaction is presented in FIG. 9.

¹H-NMR spectra of multi-PEO fullerenes in CDCl₃ (FIG. 10) give verybroad signals, no signal of fullerene carbon was observed from ¹³C-NMRspectra. Both indicate the existence of radicals and (or) randomadditions of PEG chains to fullerene molecules.

As seen in FIGS. 11A and 11B, two types of radicals were discovered fromEPR study of (PEO₃)_(m)C₆₀ solid and solution samples. The resultsindicate that some (PEO₃)_(m)C₆₀ molecules (<1% from calculation) haveradicals and small amount of Cu(II) residue still left in the sample(both organic (FIG. 11A) and transitional metal (FIG. 11B) radicalsignals). TABLE 1 Elemental analysis result of (PEO₃)_(m)C₆₀ Sample ID %C % H % Br % Cu C60TEGN 72.82 5.64 1.57 0.79

Elemental analysis of (PEO₃)_(m)C₆₀ (Table 1, above) confirmed theexistence of Br and Cu(II) residues. Calculation based on the ratio of Hgives 5 PEO₃ chains attached to each fullerene molecule by average,which is confirmed by MALDI spectrum of (PEO₃)_(m)C₆₀ (see FIG. 12 with(PEO₃)_(m)C₆₀ (FIG. 12A) and (PEO₈)_(m)C₆₀ (FIG. 12B)). When longer PEOchains were used in the reaction, fewer numbers of PEOs were reacted toeach fullerene molecule probably due to the steric hindrance. To furtherremove the Cu(II) residue, (PEO₃)_(m)C₆₀ was dissolved in CHCl₃ andbubbled with H₂S for 4 hours. After this process, the Cu(II) EPR signaldisappeared and the fullerene radical signal had no change.

One can see from the MALDI data of (PEO₃)_(m)C₆₀ (FIG. 12A) and(PEO₈)_(m)C₆₀ (FIG. 12B) that m is ranged from 1 to 8, with an averagenumber about 4 to 5. From the elemental analysis of (PEO₃)_(m)C₆₀, thereis 1.6% bromine, which equals about 0.4 bromine (or y˜0.4) per PEOfullerene, on average. The existence of bromine can be explained by thereactions mechanism (FIG. 9), when a PEO-benzyl radical (compound 2)reacted with a fullerene double bond, a fullerene radical (compound 3)formed. This fullerene radical reacted with either another PEO-benzylradical to give compound 5 or reversible abstracted bromine from thecopper complex (or perhaps compound 1) to give compound 4. Again, anypossible bromine is not shown in FIG. 3 since the bromine had no obviouseffect on the final PCMs.

Specifically, the exemplary azide addition fullerenes orC₆₀{(NCH₂CH₂O)_(n)CH₃}_(m) molecules, made with various length of PEOchains, were synthesized by azide addition of PEO-azide to fullerene (asseen in FIG. 6). As indicated above, the synthesis followed theprocedure from literature. [Hawker, C. J., Saville, P. M., and White, J.W., J. Org. Chem. 1994, 59, 3503 and Huang, X. D., Goh, S. H., and Lee,S. Y., Macromol. Chem. Phys. 2000, 201, 2660.] Once again, unlike thosefullerene azide addition reactions, in which mono-azide additionproducts are always the major products, here we found bis-azide additionproducts (compounds 5 in FIG. 6 or the Di PEOC₆₀ with n=8, 11, 16, and45 seen FIG. 2) were the major products in all the reactions. Only traceamount of mono-azide addition products (compounds 4 in FIG. 6 or theMono PEOC₆₀with n=8, 11, 16, and 45 seen FIG. 2) were detected. Thestructure of compounds 4 and 5 were confirmed by ¹H-NMR, ¹³C-NMR andelemental analysis. DSC and TGA studies showed that these materials arethermally stable up to 220° C.

The bis-azide addition fullerenes are very soluble in common organicsolvents such as toluene, methylene chloride, chloroform, THF andmethanol. Di (PEO₁₆)C₆₀ and Di (PEO₄₅)C₆₀ are soluble in water. UV—VISspectra of Di (PEO₁₆)C₆₀ in various solvents and thin film are shown inFIG. 13. The large shifts of UV absorption in different solventsstrongly indicate aggregation of these molecules.

Example 3 Membrane/Film Preparation

1. Appropriate amounts of the C₆₀(CN)₃H (it is noted that any hydrogencyano fullerene may be used for the exemplary C₆₀(CN)₃H proton-sourceagent) and, if desired, PEO_(m)C₆₀ (mixing agent) were weighed and addedto ˜5 g of Chlorobenzene.

2. Required amount of any desired PEO (host polymer) was added to ˜5 gof chlorobenzene in a separate container.

3. These mixtures were sonicated (˜10 mins).

4. They were then stirred in an 85° C. oil bath for 1˜2 hours.

5. After confirming complete dissolution, they were mixed together andstirred for about 1 hour at 85° C. in an oil bath. (PEO tends to gel ifthe mixing in the earlier stages is not proper.)

6. The resultant homogeneous solution was poured into a TEFLON dish anddried in a 120° C. oven for 2˜3 hours to get a composite film.

Example 4 Conductivity/Impedance Analysis

An HP LF4192A Impedance Analyzer was used to measure impedance(conductivity). Samples were scanned at frequencies from 0.5 Hz to 11MHz. The high frequency impedance at zero phase angle was used as theimpedance value. For each sample, the polymer film was mounted in aTEFLON fixture having windows for equilibrating with the surroundingatmosphere. The sample films were equilibrated at the required humidityfor ˜12 hours. The various humidities were achieved by saturated saltsolutions of various appropriate salts. Each resulted in a differenthumidity in the head space above the solution (a standard technique thatis well known in the art). Each sample was suspended (in the TEFLONfixture) above these salt solutions and measured after equilibration.All measurements were two-probe measurements. For the samples, all wereat room temperature (i.e. ˜22° C.) and an appropriate humidity (mostcommonly, humidity was ˜15-17% RH, but other RHs were utilized for someexperiments). The conductivity was calculated from the impedance as seenin Equation 1, immediately below.Conductivity [S/cm]=(1/R)*(L/A)   Equation 1

In Equation 1: R [Ohms]=high frequency zero phase angle resistance; L[cm]=length of the conducting film; and A [square cm]=cross sectionalarea of the conducting film (product of width and thickness of the filmfor in=plane measurements).

Example 5 First PCM Creation and Analysis Experiments

A specific PCM was prepared (see details above) by mixing poly(ethyleneoxide) (70 wt %), hydrogen tri-cyano fullerene (20 wt %), and multiplePEO C₆₀ (in which n=3 and m=5 in FIG. 3) (10 wt %) altogether andthrough solution casting. Then, the proton conductivity was measured at30° C. under 20% relative humidity. Similarly, the conductivity ofNAFION 117 was also measured as a control. Table 2 summarizes theresults. TABLE 2 Proton Conductivities of PCMs made with the HydrogenCyano Fullerene/Poly(ethylene oxide)/Multiple PEO C₆₀ (Subject Sample)versus NAFION 117. Subject Sample NAFION 117 σ, S cm⁻¹ σ, S cm⁻¹ 6 ×10⁻² 1 × 10⁻³

The results (Table 2, above) show more than an order of magnitude higherconductivity for the subject PCM than with the industrial standardNAFION 117 PCM, the control. Additionally, the results shown in Table 2demonstrate the ability of C₆₀H(CN)₃ to impart conductivity to anon-conducting polymer, such as PEO.

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Although the description above contains many details, these should notbe construed as limiting the scope of the invention but as merelyproviding illustrations of some of the presently preferred embodimentsof this invention. Therefore, it will be appreciated that the scope ofthe present invention fully encompasses other embodiments which maybecome obvious to those skilled in the art, and that the scope of thepresent invention is accordingly to be limited by nothing other than theappended claims, in which reference to an element in the singular is notintended to mean “one and only one” unless explicitly so stated, butrather “one or more.” All structural, chemical, and functionalequivalents to the elements of the above-described preferred embodimentthat are known to those of ordinary skill in the art are expresslyincorporated herein by reference and are intended to be encompassed bythe present claims. Moreover, it is not necessary for a composition ormethod to address each and every problem sought to be solved by thepresent invention, for it to be encompassed by the present claims.Furthermore, no element, composition, or method step in the presentdisclosure is intended to be dedicated to the public regardless ofwhether the element, composition, or method step is explicitly recitedin the claims. No claim element herein is to be construed under theprovisions of 35 U.S.C. 112, sixth paragraph, unless the element isexpressly recited using the phrase “means for.”

1-28. (canceled)
 29. A derivatized fullerene having the formulaC₆₀H(CN)_(n), wherein n>1.
 30. A derivatized fullerene having theformula C₆₀H(CN)₃.
 31. A derivatized fullerene having the formulaC₆₀(CN)_(n), wherein n>2.
 32. A derivatized fullerene having the formulaC₆₀(CN)₄.
 33. A method of synthesizing a hydro cyano fullerenecomprising the steps: a) providing a solubilized cyano fullerene; b)adding solubilized metallic cyanide; c) treating the above mixture withperchloric acid; and d) isolating the hydro cyano fullerene product. 34.A method of synthesizing a hydro cyano fullerene having the formulaC₆₀H(CN)_(n), wherein n>1, comprising the steps: a) providingsolubilized C₆₀(CN)_(n), wherein n>1; b) adding solubilized metalliccyanide; c) treating the above mixture with perchloric acid; and d)isolating the C₆₀H(CN)_(n), wherein n>1, product.
 35. A method ofsynthesizing a hydro cyano fullerene having the formula C₆₀H(CN)₃,comprising the steps: a) providing solubilized C₆₀(CN)₂; b) addingsolubilized sodium cyanide; c) treating the above mixture withperchloric acid; and d) isolating the C₆₀H(CN)₃ product.